Lightweight Web Servers

I’ve been using the excellent Uptime Kuma for my monitoring, but a couple of recent incidents - an external USB mount disappeared on a remote machine, an NVME drive filled up on a different node and stopped backups working because of a configuration error - have made me start to think about more robust monitoring.

The are many great tools for this - Nagios , Prometheus etc. but they are pretty substantial time investments for the excellent power. They can save time series data and display them beautifully. However, all I really want is to add some extra ability to Uptime Kuma.